Robot cleaner and control method for the same

ABSTRACT

A robot cleaner includes a body to travel on a floor, an obstacle sensing unit to sense an obstacle approaching the body, an auxiliary cleaning unit mounted to a bottom of the body, to be extendable and retractable, and a control unit to control extension or retraction of the auxiliary cleaning unit when the obstacle is sensed. The control unit recognizes a zone of a charger and performs a control operation to prevent the auxiliary cleaning unit from extending in the charger zone.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Korean Patent Application Nos.10-2011-108221 and 10-2012-22470, respectively filed on Oct. 21, 2011and Mar. 5, 2012 in the Korean Intellectual Property Office, thedisclosures of which are incorporated herein by reference.

BACKGROUND

1. Field

Embodiments of the present disclosure relate to a robot cleaner and acontrol method for the same, which are capable of automatically cleaninga region to be cleaned by removing dust or the like from a floor of thecleaning region while traveling about the cleaning region.

2. Description of the Related Art

A robot cleaner is a device for automatically cleaning a region to becleaned by sucking foreign matter such as dust from a floor of thecleaning region while autonomously traveling about the cleaning regionwithout user control. Such a robot cleaner not only includes a mainbrush to remove dust or the like accumulated on a region beneath a bodyof the robot cleaner, but also includes an auxiliary cleaning tool toachieve an enhancement in cleaning performance in a region adjacent to awall.

Such an auxiliary cleaning tool is outwardly protruded from an inside ofthe robot cleaner body, to sweep dust on a floor, in particular, dust ina region adjacent to a wall. Although such an auxiliary cleaning toolachieves an enhancement in cleaning performance in a region adjacent toa wall, there may be a problem in that the auxiliary cleaning tool hasan increased possibility of striking the wall because it is outwardlyprotruded from the robot cleaner body.

In particular, in a conventional robot cleaner system, the robot cleanerthereof may not discriminate an additional device included in the robotcleaner system, for example, a charger or a virtual obstacle zoneforming device, from obstacles. In this case, the robot cleaner mayapproach the additional device of the robot cleaner system and, as such,the auxiliary cleaning tool thereof may extend. As a result, theauxiliary cleaning tool may strike the additional device, therebyshifting the position of the additional device or damaging theadditional device. To this end, it may be necessary to provide a robotcleaner capable of discriminating the additional device of the robotcleaner system from obstacles.

SUMMARY

Therefore, it is an aspect of the present disclosure to provide a robotcleaner and a control method for the same, which are capable ofperforming a control operation such that, although an obstacle on atravel path is sensed, the auxiliary cleaning unit of the robot cleanerdoes not extend when the sensed obstacle is a zone of an additionaldevice constituting a robot cleaner system.

Additional aspects of the disclosure will be set forth in part in thedescription which follows and, in part, will be apparent from thedescription, or may be learned by practice of the disclosure.

In accordance with one aspect of the present disclosure, a robot cleanerincludes a body to travel on a floor, an obstacle sensing unit to sensean obstacle approaching the body, an auxiliary cleaning unit mounted toa bottom of the body, to be extendable and retractable, and a controlunit to control extension or retraction of the auxiliary cleaning unitwhen the obstacle is sensed. The control unit may recognize a zone of acharger and perform a control operation to prevent the auxiliarycleaning unit from extending in the charger zone.

The control unit may create and store a cleaning region map includinginformation about a travel path of the body.

The control unit may designate a start position of the travel path ofthe body to a position of the charger in the cleaning region map,recognize the charger zone based on the charger position designated inthe cleaning region map, and perform a control operation to cause thebody to travel while bypassing the charger zone.

The control unit may determine a charging state of the body.

The control unit may determine that the body is positioned at thecharger zone when the body is in a charging state.

The controller may determine that the body is positioned at the chargerzone for a predetermined time, when the body travels backward aftercompletion of charging.

The robot cleaner may further include a signal sensing unit to sense asignal transmitted from the charger. The control unit may recognize thecharger zone based on the signal, and perform a control operation tocause the body to travel while bypassing the charger zone.

The signal may be a signal to guide travel of the body toward thecharger, for docking of the body with the charger.

The signal may include at least one of an infrared signal, an ultrasonicsignal and a laser signal, which are forwardly or laterally transmittedfrom the charger within a predetermined angular range.

The signal may be divided into two signals, which overlap each other andhave different ranges or different intensities.

The signal may form, as the charger zone, a zone having a predeterminedcurved surface at a front or lateral side of the charger.

The signal may include at least one of an infrared signal, an ultrasonicwave signal and a laser signal, each of which forms a signal zone havinga predetermined curved surface at the front or lateral side of thecharger.

The signal may be divided into two signals, which overlap each other andhave different ranges or different intensities.

The control unit may determine that the body is positioned at thecharger zone, when the signal is sensed in a stopped state of the body.

The control unit may create and store a cleaning region map includinginformation about a travel path of the body, designate a position, fromwhich the signal is transmitted, to a position of the charger in thecleaning region map, recognize the charger zone based on the chargerposition designated in the cleaning region map, and perform a controloperation to cause the body to travel while bypassing the charger zone.

In accordance with another aspect of the present disclosure, a robotcleaner includes a body to travel on a floor, an obstacle sensing unitto sense an obstacle approaching the body, an auxiliary cleaning unitmounted to a bottom of the body, to be extendable and retractable, and acontrol unit to control extension or retraction of the auxiliarycleaning unit when the obstacle is sensed. The control unit mayrecognize an extension prevention zone and perform a control operationto prevent the auxiliary cleaning unit from extending in the extensionprevention zone.

The robot cleaner may further include a signal sensing unit to sense asignal transmitted from an extension prevention signal generating unit.The control unit may recognize the extension prevention zone based onthe signal. The extension prevention zone may be formed by the signaltransmitted from the extension prevention signal generating unit.

The signal may form a virtual obstacle zone extending from the extensionprevention signal generating unit in one direction while having apredetermined size. The control unit may perform a control operation tocause the body to travel while bypassing the virtual obstacle zone.

The signal may form a rectilinear virtual wall zone having apredetermined thickness and a predetermined length.

The signal may include at least one of an infrared signal, an ultrasonicwave signal and a laser signal, which are transmitted from the extensionprevention signal generating unit in one direction within apredetermined angular range.

The signal may form a virtual obstacle zone having a predeterminedcurved surface around the extension prevention signal generating unit.The control unit may perform a control operation to cause the body totravel while bypassing the virtual obstacle zone.

The signal may include at least one of an infrared signal, an ultrasonicwave signal and a laser signal, each of which forms a signal zone havinga predetermined curved surface at the front or lateral side of thecharger.

The robot cleaner may further include a signal sensing unit to sense amagnetic field signal. The control unit may recognize the extensionprevention zone based on the magnetic field signal. The extensionprevention zone may be a magnetic field zone formed by a magnetic beltinstalled on the floor.

The control unit may perform a control operation to cause the body totravel while bypassing the magnetic field zone.

In accordance with another aspect of the present disclosure, a controlmethod for a robot cleaner including a body to travel on a floor, anobstacle sensing unit to sense an obstacle approaching the body, and anauxiliary cleaning unit mounted to a bottom of the body, to beextendable and retractable includes controlling the body to clean thefloor while traveling on the floor, sensing an obstacle on a travel pathof the body, and controlling the auxiliary cleaning unit to extend orretract when the obstacle is sensed, recognizing a zone of a charger,and controlling the auxiliary cleaning unit to be prevented fromextending in the charger zone upon recognition of the charger zone.

The recognizing the charger zone may include designating a startposition of the travel path of the body to a position of the charger ina cleaning region map including information about the travel path of thebody, and recognizing the charger position designated in the cleaningregion map as the charger zone.

The recognizing the charger zone may include sensing a charging state ofthe body, and determining that the body is positioned at the chargerzone, when the body is in a charging state.

The recognizing the charger zone may include sensing a chargingcompletion state of the body, and determining that the body ispositioned at the charger zone for a predetermined time, when the bodytravels backward after completion of charging.

The recognizing the charger zone may include sensing a signaltransmitted from the charger, and recognizing the charger zone based onthe sensed signal.

The signal may be a signal to guide travel of the body toward thecharger, for docking of the body with the charger or a signal to form,as the charger zone, a zone having a predetermined curved surface at afront or lateral side of the charger.

The recognizing the charger zone may include determining that the bodyis positioned at the charger zone, when the signal is sensed in astopped state of the body.

The recognizing the charger zone may include designating a position,from which the signal is transmitted, to a position of the charger in acleaning region map including information about a travel path of thebody, and recognizing the charger zone based on the charger positiondesignated in the cleaning region map.

In accordance with still another aspect of the present disclosure, acontrol method for a robot cleaner including a body to travel on afloor, an obstacle sensing unit to sense an obstacle approaching thebody, and an auxiliary cleaning unit mounted to a bottom of the body, tobe extendable and retractable includes controlling the body to clean thefloor while traveling on the floor, sensing an obstacle on a travel pathof the body, and controlling the auxiliary cleaning unit to extend orretract when the obstacle is sensed, recognizing an extension preventionzone, and controlling the auxiliary cleaning unit to be prevented fromextending in the extension prevention zone upon recognition of theextension prevention zone.

The recognizing the extension prevention zone may include sensing asignal transmitted from an extension prevention signal generating unit,and recognizing the extension prevention zone based on the signal, andthe extension prevention zone is formed by the signal transmitted fromthe extension prevention signal generating unit.

The signal may form a virtual obstacle zone extending from the extensionprevention signal generating unit in one direction while having apredetermined size or a virtual obstacle zone having a predeterminedcurved surface around the extension prevention signal generating unit.The recognizing the extension prevention zone may include controllingthe body to travel while bypassing the virtual obstacle zone.

The recognizing the extension prevention zone may include sensing amagnetic field signal, and recognizing the extension prevention zonebased on the magnetic field signal. The extension prevention zone may beformed by a magnetic belt installed on the floor.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects of the disclosure will become apparent andmore readily appreciated from the following description of theembodiments, taken in conjunction with the accompanying drawings ofwhich:

FIG. 1 is a view schematically illustrating an outer appearance of arobot cleaner according to an exemplary embodiment of the presentdisclosure;

FIG. 2 is a bottom view schematically illustrating a configuration ofthe robot cleaner shown in FIG. 1;

FIG. 3 is a view schematically illustrating a configuration forextending or retracting auxiliary cleaning units in accordance with anembodiment of the present disclosure;

FIG. 4 is a view schematically illustrating a configuration forextending or retracting the auxiliary cleaning units in accordance withanother embodiment of the present disclosure;

FIG. 5 is a view schematically illustrating a configuration of anauxiliary cleaning tool according to an exemplary embodiment of thepresent disclosure;

FIG. 6 is a view schematically illustrating a configuration of theauxiliary cleaning tool according to another embodiment of the presentdisclosure;

FIG. 7 is a block diagram schematically illustrating a controlconfiguration of the robot cleaner according to an exemplary embodimentof the present disclosure;

FIGS. 8A to 8D are views schematically illustrating an operation of therobot cleaner to recognize a charger zone in accordance with anexemplary embodiment of the present disclosure;

FIG. 9 is a view schematically illustrating an operation of the robotcleaner to recognize a charger zone in accordance with anotherembodiment of the present disclosure;

FIG. 10 is a view schematically illustrating an operation of the robotcleaner to recognize a charger zone in accordance with anotherembodiment of the present disclosure;

FIGS. 11 and 12 are views schematically illustrating an operation of therobot cleaner to recognize a charger zone in accordance with anotherembodiment of the present disclosure;

FIG. 13 is a view schematically illustrating an operation of the robotcleaner to recognize a charger zone in accordance with anotherembodiment of the present disclosure;

FIG. 14 is a view schematically illustrating an operation of the robotcleaner to recognize a charger zone in accordance with anotherembodiment of the present disclosure;

FIG. 15 is a view schematically illustrating an operation of the robotcleaner to recognize a virtual obstacle zone in accordance with anexemplary embodiment of the present disclosure;

FIG. 16 is a view schematically illustrating an operation of the robotcleaner to recognize a virtual obstacle zone in accordance with anotherembodiment of the present disclosure;

FIG. 17 is a flowchart schematically illustrating a method forcontrolling the robot cleaner in accordance with an exemplary embodimentof the present disclosure; and

FIG. 18 is a flowchart schematically illustrating a method forcontrolling the robot cleaner in accordance with another embodiment ofthe present disclosure.

DETAILED DESCRIPTION

Hereinafter, embodiments of the present disclosure will be describedwith reference to the accompanying drawings.

FIG. 1 is a view schematically illustrating an outer appearance of arobot cleaner according to an exemplary embodiment of the presentdisclosure.

Referring to FIG. 1, the robot cleaner, which is designated by referencenumeral “1”, includes a body 10 to define an outer appearance of therobot cleaner 1.

Various sensors are mounted to the body 10, to sense an obstacle. Thesensors may include a proximity sensor 61 and/or a vision sensor 62. Forexample, when the robot cleaner 1 travels in a random direction underthe condition that there is no predetermined path, along which the robotcleaner 1 travels, that is, in a cleaning system having no map, therobot cleaner 1 may travel about a cleaning region and sense anobstacle, using the proximity sensor 61. On the other hand, when therobot cleaner 1 travels along a predetermined path, that is, in acleaning system requiring a map, the vision sensor 62 may be installedto receive position information of the robot cleaner 1, and thus tocreate a map. The sensors may be implemented in various manners.

A signal sensor 63 may also be mounted to the body 10, to receive asignal from a charger or an exhaust station.

A display unit 64 is coupled to the body 10, to display various statesof the robot cleaner 1. For example, the display unit 64 may display acharged state of the battery, whether or not the dust collector 55 isfull of dust, a cleaning mode of the robot cleaner 1, etc.

Configurations of the auxiliary cleaning units 21 and 22 will bedescribed in more detail with reference to FIGS. 3 to 6.

FIG. 2 is a bottom view schematically illustrating a configuration ofthe robot cleaner shown in FIG. 1.

Referring to FIGS. 1 and 2, the robot cleaner 1 includes a main brushunit 30, a power supply 50, drive wheels 41 and 42, a caster 43, and theauxiliary cleaning units 21 and 22.

The main brush unit 30 is mounted at an opening formed at a portion ofthe bottom of the body 10 biased from a central region of the body 10 ina rearward direction R. The main brush unit 30 sweeps dust accumulatedon the floor, on which the body 10 is disposed, such that the swept dustis guided to a dust inlet 33. The opening of the bottom of the body 10,at which the main brush unit 30 is mounted, functions as the dust inlet33.

The main brush unit 30 includes a roller 31, and a main brush 32 stuckin an outer surface of the roller 31. As the roller 31 rotates, the mainbrush 32 sweeps dust accumulated on the floor such that the swept dustis guided to the dust inlet 33.

Although not shown in FIG. 2, a fan unit to generate suction force isprovided within the dust inlet 33. The fan unit functions to move dustintroduced into the dust inlet 33 to a dust collector.

The power supply 50 supplies drive power to drive the body 10. The powersupply 50 includes a battery electrically connected to the body 10 anddrivers to drive various elements mounted to the body 10, to supplydrive power to the body 10 and drivers. The battery is constituted by arechargeable secondary battery. When the body 10 is coupled to a chargeror an exhaust station after completing a cleaning operation, the batteryreceives electric power from the charger or exhaust station, to becharged.

The drive wheels 41 and 42 are centrally arranged at opposite sides ofthe bottom of the body 10 in a symmetrical manner, respectively. Thedrive wheels 41 and 42 may perform movement operations including forwardmovement, backward movement, and rotation during cleaning.

The caster 43 is installed at a front edge portion of the bottom of thebody 10 when viewed on the basis of a travel direction. The caster 43enables the body 10 to maintain a stable posture. The drive wheels 41and 42, and caster 43 may be configured into a single assemblydetachably mounted to the body 10.

Openings are formed at opposite sides of a front portion of the body 10when viewed on the basis of a forward direction F, respectively. Theauxiliary cleaning units 21 and 22 are installed to cover the openings,respectively.

FIG. 3 is a view schematically illustrating a configuration forextending or retracting the auxiliary cleaning units in accordance withan embodiment of the present disclosure.

Referring to FIG. 3, each of the auxiliary cleaning units 21 and 22includes a side arm 102, a periphery cover 103, and an auxiliarycleaning tool 110.

The side arm 102 is coupled to a front portion of the bottom of the body10 at one side of the body 10. An arm motor (not shown) is received inthe body 10 over the side arm 102, to drive the side arm 102. The armmotor is connected to a rotation shaft (not shown) via gears to transmitdrive force to the side arm 102. The rotation shaft is mounted to acoupling groove 101 formed at one end of the side arm 102.

When the arm motor is driven, the rotation shaft is rotated, therebycausing the side arm 102 to pivot about the coupling groove 101. In thiscase, the side arm 102 pivots outwardly of the body 10. In this state,the periphery cover 103 no longer covers the opening of the body 10.That is, the periphery cover 103 no longer forms the periphery of thebody 10.

A coupling groove 104, to which the auxiliary cleaning tool 110 iscoupled, is formed at the other end of the side arm 102. A rotationmotor (not shown) is received in the body 10 over the coupling groove104, to drive the auxiliary cleaning tool 110. The auxiliary cleaningtool 110 is rotated about the coupling groove 104 by drive force of therotation motor.

FIG. 4 is a view schematically illustrating a configuration forextending or retracting the auxiliary cleaning units in accordance withanother embodiment of the present disclosure.

Referring to FIG. 4, each of the auxiliary cleaning units 21 and 22includes a side arm 106, a periphery cover 108, and an auxiliarycleaning tool 110.

The side arm 106 is coupled to a front portion of the bottom of the body10 at one side of the body 10 via a coupling groove 105. An extensionarm 107 is received in the side arm 106 such that it is extendableoutwardly of the side arm 106 in a sliding manner.

The extension arm 107 moves forward and rearward within the side arm 106in a longitudinal direction of the side arm 106. To this end, a rail isformed within the side arm 106, and a guide (not shown), which isengaged with the rail, is formed at the extension arm 107. Accordingly,the extension arm 107 may slidably move along the rail in a state ofbeing coupled to the rail. Another extension arm may be received in theextension arm 107 such that it is extendable outwardly of the extensionarm 107 in a sliding manner. Meanwhile, movement of the anotherextension arm may be carried out in the same manner as described above.There is no limitation as to the number of extension arms.

An arm motor (not shown) is received in the body 10 over the side arm106, to drive the extension arm 107. The arm motor transmits drive forceto the extension arm 107 via gears. When the arm motor is driven, theextension arm 107 slides outwardly of the side arm 106, to extendoutwardly of the body 10. In this state, the periphery cover 108 nolonger covers the opening of the body 10. That is, the periphery cover108 no longer forms the periphery of the body 10.

A coupling groove 109, to which the auxiliary cleaning tool 110 iscoupled, is formed at one end of the extension arm 107. A rotation motor(not shown) is received in the body over the coupling groove 109, todrive the auxiliary cleaning tool 110. The auxiliary cleaning tool 110is rotated about the coupling groove 109 by drive force of the rotationmotor.

FIG. 5 is a view schematically illustrating a configuration of theauxiliary cleaning tool according to an exemplary embodiment of thepresent disclosure.

Referring to FIG. 5, the auxiliary cleaning tool 110 includes brush arms113 coupled to form a central common end such that they outwardly extendin a radial direction from the central common end while being spacedapart from one another in a circumferential direction. An auxiliarybrush 112 is coupled to each brush arm 113. A rotation shaft 114 isformed at the central common end of the brush arms 113. The rotationshaft 114 extends to be coupled to the side arm 102 or extension arm 106via the coupling groove 104 or 109. When the auxiliary cleaning tool 110rotates, the auxiliary brush 112 sweeps dust accumulated on an areadisposed adjacent to a wall toward the central region of the body 10 ordisperses the dust.

FIG. 6 is a view schematically illustrating a configuration of theauxiliary cleaning tool according to another embodiment of the presentdisclosure.

Referring to FIG. 6, the auxiliary cleaning tool 110′ includes acircular floorcloth holder 116. An auxiliary floorcloth 115 is fittedaround the floorcloth holder 116 in a radial direction. A rotation shaft114 is formed at a center of the floorcloth holder 116 such that itaxially extends. The rotation shaft 114 receives drive force from arotation motor, to rotate the auxiliary cleaning tool 110′. The rotationshaft 114 is coupled to the side arm 102 or extension arm 106 via thecoupling groove 104 or 109. When the auxiliary cleaning tool 110′rotates, the auxiliary floorcloth 115 scrubs an area disposed adjacentto a wall.

Meanwhile, the auxiliary brush 112 may be made of various materialshaving elasticity. The auxiliary floorcloth 115 may be made of a fibermaterial or various materials other than the fiber material.

The robot cleaner 1 according to the illustrated embodiment of thepresent disclosure may clean even an area of the floor disposed adjacentto a wall or a corner area of the floor because the effective cleaningregion of the robot cleaner 1 is extended by virtue of the auxiliarycleaning units 21 and 22 outwardly extendable from the body 10.

In the following description, it is assumed that extension of eachauxiliary cleaning unit 21 or 22 carried out during operation of theauxiliary cleaning unit 21 or 22 include both pivotal movement of theside arm 102 outwardly of the body 10 in the embodiment of FIG. 3 andextension of the extension arm 106 outwardly of the body 10 in theembodiment of FIG. 4, except for the case in which the extension of eachauxiliary cleaning unit 21 or 22 is separately described in conjunctionwith pivotal movement of the side arm 102 or the extension of theextension arm 106. Also, it is assumed that the auxiliary cleaning tool110 cleans an area of the floor disposed adjacent to a wall or a cornerarea of the floor while rotating during cleaning operation of the robotcleaner 1.

FIG. 7 is a block diagram schematically illustrating a controlconfiguration of the robot cleaner according to an exemplary embodimentof the present disclosure.

Referring to FIG. 7, the robot cleaner 1 includes an input unit 210, anobstacle sensing unit 220, a signal sensing unit 230, a control unit240, a body driver 250, a main brush unit driver 260, and an auxiliarycleaning unit driver 270.

The input unit 210 receives a user's operation command from an operationpanel provided at the body 10 or a remote controller. The user'soperation command includes commands associated with travel, cleaning andcharging operations of the robot cleaner 1. In particular, the userdirectly operates the remote controller, to input a command associatedwith, for example, protrusion of the auxiliary cleaning units 21 and 22.

The obstacle sensing unit 220 senses an obstacle approaching the body 10during travel of the body 10. In more detail, the obstacle sensing unit220 receives information as to obstacles from the proximity sensor 61 orvision sensor 62, and then senses an obstacle disposed around the body10.

For example, the proximity sensor 61 may be implemented in the form ofan ultrasonic sensor. In this case, the proximity sensor 61 may transmitan ultrasonic wave, and then receive an ultrasonic wave reflected froman obstacle, thereby sensing the obstacle. For this function, theproximity sensor 61 may take the form of a combination of at least oneultrasonic transmitter and at least one ultrasonic receiver installedaround the periphery of the body 10. When the ultrasonic proximitysensor 61 further approaches an obstacle, it generates a signal havinghigher power because the intensity of an ultrasonic wave received by theultrasonic proximity sensor 61 after being reflected from the obstacleincreases. It may be possible to calculate the distance between the body10 and the obstacle, based on the output signal from the proximitysensor 61.

Meanwhile, the vision sensor 62 acquires an image on the travel path ofthe body 10, and then senses an obstacle through processing of theacquired image. Practically, it may be possible to calculate thedistance between the body 10 and the obstacle in the image processed bythe vision sensor 62, based on three-dimensional coordinates.

The signal sensing unit 230 senses an identifying signal transmittedfrom the charger or formed around the charger in accordance withoperation of the signal sensor 63.

The body driver 250 drives the drive wheels 41 and 42, to move the robotcleaner 1. In accordance with a control command from a travel controller242, the body driver 250 controls the travel direction and travel speedof the robot cleaner 1.

The main brush unit driver 260 drives the roller 31 in accordance with acontrol command from a cleaning controller 241. In accordance withrotation of the roller 31, the main brush 32 sweeps dust accumulated onthe floor.

The auxiliary cleaning unit driver 270 drives the arm motor inaccordance with a control command from the cleaning controller 241, toperform extension or retraction of each auxiliary cleaning unit 21 or22. The auxiliary cleaning unit driver 270 also adjusts an extension orretraction degree of each auxiliary cleaning unit 21 or 22 by adjustingthe number of rotations of the arm motor in accordance with the distancebetween the body 10 and the obstacle. The auxiliary cleaning unit driver270 also performs rotation of the auxiliary cleaning tool 110 andadjusts the rotation speed of the auxiliary cleaning tool 110, to causethe auxiliary brush 112 (or the rotation speed of the auxiliary cleaningtool 110′, to cause auxiliary floorcloth 115) to clean an area disposedadjacent to a wall.

The control unit 240 controls the overall operation of the robot cleaner1 in accordance with a control program. The control unit 240 mainlyincludes the cleaning controller 241, which controls cleaning operationof the robot cleaner 1, the travel controller 242, which controls travelof the robot cleaner 1, and a charging controller 243 to controlcharging operation of the robot cleaner 1.

The cleaning controller 241 not only controls operation of the mainbrush unit 30, but also determines whether each auxiliary cleaning unit21 or 22 is to be extended or retracted. The cleaning controller 241also controls an extension or retraction degree of each auxiliarycleaning unit 21 or 22. Also, the cleaning controller 241 determines anoperation mode of the robot cleaner 1 among an automatic cleaning mode,a charging mode, a charging completion mode, a charging stop mode, etc.,and controls extension or retraction of each auxiliary cleaning unit 21or 22 in accordance with the determined operation mode.

The travel controller 242 controls forward movement, backward movementand rotation of the body 10. In more detail, the travel controller 242controls rotation directions and speed of the drive wheels 41 and 42.When it is sensed that there is an obstacle on the travel path of thebody 10, the travel controller 242 also determines whether the body 10has to turn to the left or to the right or has to move backward.

The charging controller 243 controls the robot cleaner 1 to return tothe charger or to the exhaust station when cleaning operation iscompleted, to cause the robot cleaner 1 to be charged. When chargingoperation is carried out in a state in which the body 10 docks with thecharger, the charging controller 243 determines a charged state of therobot cleaner 1. That is, the charging controller 243 may determine acompletely charged state, a power shut-off state of the charger duringcharging operation, etc.

Hereinafter, methods for controlling extension and retraction of theauxiliary cleaning units of the above-described robot cleaner inaccordance with embodiments of the present disclosure will be described.

FIGS. 8A to 8D are views schematically illustrating an operation of therobot cleaner to recognize a charger zone in accordance with anexemplary embodiment of the present disclosure.

Referring to FIG. 8A, the body 10 is in contact with the charger 80, forcharging. When the body 10 is in contact with the charger 80, thecharging controller 241 determines that the body 10 is being charged,namely, in a charging state.

When the body 10 is completely charged or in accordance with anautomatic cleaning command from the user, the body 10 is separated fromthe charger 80 and starts travel about a cleaning region. The body 10removes dust on the floor while traveling about the cleaning regionalong a predetermined travel path. To this end, the travel controller242 creates and stores a cleaning region map including the travel pathinformation of the body 10.

Meanwhile, in this case, the cleaning start position of the body 10corresponds to the position of the charger 80, unless the user moves thebody 10, which is being charged while in contact with the charger 80,from the charger 80 to another position after separating the body 10from the charger 80.

Referring to FIG. 8B, the travel controller 242 creates a cleaningregion map, and stores travel regions D corresponding to the travel pathof the body 10. The body 10 removes dust from the floor while travelingabout the travel regions D along the travel path. The travel controller242 also stores information about a cleaning completion state of eachtravel region D. Thus, the body 10 removes dust while sequentiallytraveling about travel regions D, for which cleaning has not beencompleted, based on the stored cleaning completion state informationfrom the travel controller 242.

Also, the travel controller 242 may designate the position of thecharger 80 to a travel path start position of the body 10. Thus, thetravel controller 242 may recognize a charger zone C based on theposition of the charger 80 designated in the cleaning region map.

Meanwhile, as shown in FIG. 8B, when the body 10 travels while followinga wall, the auxiliary cleaning unit disposed at the side of the wall,for example, the right auxiliary cleaning unit 21, removes dust from anarea disposed adjacent to the wall while being in an extended state.Although the right auxiliary cleaning unit 21 is illustrated astraveling while being in an extended state, in FIG. 8B, embodiments ofthe present disclosure are not limited thereto. For example, when thebody 10 travels while following a left wall, the left auxiliary cleaningunit 22 may travel while being in an extended state in the same manneras described above.

Referring to FIG. 8C, an obstacle 0 may be disposed on the travel pathof the body 10. When the obstacle 0 is sensed while the body 10 travelsabout travel regions D along the travel path, the cleaning controller241 performs a control operation to extend the auxiliary cleaning unit21.

In particular, when an obstacle is sensed on the travel path of the body10 only at one side of the body, the corresponding auxiliary cleaningunit, for example, the auxiliary cleaning unit 21, may be controlled tobe retracted into the body 10 after being temporarily outwardly extendedfrom the body 10. Since the control for the auxiliary cleaning unit 21is carried out in a real time manner, the auxiliary cleaning unit 21 maybe continuously driven when the obstacle 0 is continuously sensed, eventhough the auxiliary cleaning unit 21 has been controlled to betemporarily driven.

Referring to FIG. 8D, when the body 10 approaches the charger zone Cduring travel thereof, the obstacle sensing unit 220 may sense, as anobstacle, the charger 80 on the travel path of the body 10. When thecleaning controller 241 determines the charger 80 as an obstacle and, assuch, the auxiliary cleaning units 21 and 22 are extended, thepossibility that the body 10 strikes the charger 80 may increase. Whenthe position of the charger 80 is shifted due to striking between thebody 10 and the charger 80, it may be difficult for the body 10 toreturn to the charger 80 after completion of cleaning.

To this end, the cleaning controller 241 recognizes the charger zone C,and performs a control operation to prevent the auxiliary cleaning unitsfrom extending in the charger zone C. Also, the travel controller 242performs a control operation to prevent the body 10 from entering thecharger zone C and to control the body 10 to travel while bypassing thecharger zone C. That is, as shown in FIG. 8D, the body 10 passes atravel region D disposed adjacent to the charger zone C while bypassingthe charger zone C.

FIG. 9 is a view schematically illustrating an operation of the robotcleaner to recognize a charger zone in accordance with anotherembodiment of the present disclosure.

Referring to FIG. 9, the body 10 is provided with charging terminals 51,to contact the charging terminals 81 of the charger 80. When thecharging terminals 51 of the body 10 are in contact with the chargingterminals 81 of the charger 80, the charging controller 243 senses thatthe body 10 is in a charging state. Although FIG. 9 illustrates acharging system using contact between the body 10 and the charger 80,embodiments of the present disclosure are not limited thereto. The body10 may be charged using an electromagnetic system, even in a state inwhich the body 10 does not contact the charger 80. Also, the chargingcontroller 243 may be connected to the battery of the body 10, to sensea charging state of the body 10.

The cleaning controller 241 receives information about a charging stateof the body 10 from the charging controller 243. When it is determined,based on the received information, that the body 10 is in a chargingstate, the cleaning controller 241 determines that the body 10 isdisposed in the charger zone. When the body 10 is in the charging state,the obstacle sensing unit 220 senses the charger 80 as an obstacle, andthen prevents the auxiliary cleaning units 21 and 22 from extending.That is, it may be possible to prevent the body 10 from being separatedfrom the charger 80 due to abnormal extension of the auxiliary cleaningunits 21 and 22 or to prevent the charger 80 from being abraded due tostriking between the charger 80 and the auxiliary cleaning units 21 and22.

FIG. 10 is a view schematically illustrating an operation of the robotcleaner to recognize a charger zone in accordance with anotherembodiment of the present disclosure.

FIG. 10 illustrates a state in which the body 10 is separated from thecharger 80 in accordance with backward travel thereof carried out aftercompletion of charging. The charging controller 243 checks the residualamount of the battery of the body 10. When the residual amount of thebattery reaches a predetermined amount, the charging controller 243controls travel of the body 10, to return the body 10 to the charger 80,for charging thereof. When the body 10 completes charging, the chargingcontroller 243 performs a control operation such that the body 10 isautomatically separated from the charger 80, and then returns to thejust previous cleaning area in order to again perform the cleaningoperation on the cleaning area. When the body 10 performs backwardtravel at high speed after completion of charging in the above case, theobstacle sensing unit 220 may sense the charger 80 as an obstacle. Inthis case, the auxiliary cleaning units 21 and 22 may be extended.

To this end, when the body 10 performs backward travel after completionof charging, the cleaning controller 241 determines that the body 10 ispositioned at the charger zone, and then performs a control operation toprevent the auxiliary cleaning units 21 and 22 from extending for apredetermined time. Meanwhile, the charging controller 243 senses acharging completion state of the body 10. When charging is completed,the charging controller 243 transmits information about the chargedstate of the body 10 to the cleaning controller 241. The cleaningcontroller 241 prevents the auxiliary cleaning units 21 and 22 fromextending for a predetermined time. The predetermined time correspondsto a time taken for the body 10 to be spaced away from the charger 80 bya predetermined distance.

FIGS. 11 and 12 are views schematically illustrating an operation of therobot cleaner to recognize a charger zone in accordance with anotherembodiment of the present disclosure.

Referring to FIG. 11, the charger 80 transmits an identifying signal inorder to enable recognize of the charger 80. The signal sensing unit230, which is provided at the body 10, senses the identifying signaltransmitted from the charger 80. In detail, a plurality of signalsensors 63 is installed at the front surface or lateral surface of thebody 10, to receive a signal transmitted from the charger 80. The signalsensing unit 230 senses the identifying signal transmitted from thecharger 80, based on signals received by the signal sensors 63.

The identifying signal may be a signal to guide travel of the body 10toward the charger 80, for docking of the body 10 with the charger 80.That is, when cleaning is completed, the body 10 travels toward thecharger 80 in accordance with a travel algorithm for return of the body10 to the charger 80. In this case, the identifying signal is a signaltransmitted from the charger 80 in order to enable tracing of theposition of the charger 80, for docking of the body with the charger 80,in detail, contact between the contact terminals of the charger 80 andthe contact terminals of the body 10.

For example, a signal transmitting unit 82 to transmit an infraredsignal is installed at the charger 80. The signal transmitting unit 82forms an identifying signal zone L at the front or lateral side of thecharger 80. In this case, the signal transmitting unit 82 may transmitinfrared signals having different intensities or different ranges. Forexample, the signal transmitting unit 82 may include a first infraredsignal transmitter to transmit a low-power infrared signal, and thus toform a first infrared signal zone, and a second infrared signaltransmitter to transmit a high-power infrared signal, and thus to form asecond infrared signal zone smaller than the first infrared signal zone.Although the first and second infrared signals overlap each other, theymay be distinguished from each other in accordance with the ranges orintensities thereof.

That is, the signal transmitting unit 82 installed at the charger 80forwardly or laterally transmits an infrared signal within apredetermined angular range, to form an identifying signal zone. Ofcourse, the identifying signal is not limited to the infrared signal. Anultrasonic wave signal or a laser signal may be used in the same manneras in the infrared signal.

The signal sensors 63, which are installed at the body 10, receive theinfrared signal or the like. When the signal sensing unit 230 senses anidentifying signal, based on the signal received by the signal sensors63, the cleaning controller 241 determines that the body 10 ispositioned at the charger zone, and then performs a control operation toprevent the auxiliary cleaning units 21 and 22 from extending. That is,the cleaning controller 241 recognizes the charger zone based on theidentifying signal, and then controls the body 10 to travel whilebypassing the charger zone, and prevents the auxiliary cleaning units 21and 22 from extending. Upon sensing a signal to guide travel of the body10 while the body 10 travels along a travel path for cleaning, under thecondition in which it is unnecessary to charge the body 10 or cleaninghas not been completed, the travel controller 242 does not controltravel of the body for docking of the body 10 with the charger 80. Thisis because it is unnecessary to dock the body 10 with the charger 80 inthe above case.

Referring to FIG. 12, the identifying signal may be a signal, whichforms a zone of the charger 80. That is, the identifying signal forms acharger zone having a certain curved surface at the front or lateralside of the charger 80, to prevent the body 10 from entering the charger80. The identifying signal causes the cleaning controller 241 to sensethe charger 80 as an obstacle, thereby causing the body 10 to travelwhile bypassing the charger 80, differently than the signal to dock thebody 10 with the charger 80.

As described above, signal transmitters 83 to transmit identifyingsignals are installed at the charger 80. By the signal transmitters 83,identifying signal zones A are formed at the front and lateral sides ofthe charger 80. In this case, the identifying signals are divided into afirst identifying signal and a second identifying signal in accordancewith ranges and intensities thereof, even though they overlap with oneanother. For example, when the second signal zone is sensed, the travelcontroller 242 determines that the charger 80 is positioned on thetravel path of the body 10. In this case, the travel controller 242 maymore minutely control travel of the body 10. For example, thesensitivity of the obstacle sensing unit 220 is increased, to preventthe body 10 from striking the charger 80. When the first and secondsignals are simultaneously sensed, the travel controller 242 determinesthat there is a possibility that the body 10 strikes the charger 80. Inthis case, the travel controller 242 controls the body 10 to rotate andthen to travel while bypassing the charger 80.

The identifying signal zone A formed by the identifying signaltransmitted from the charger 80 may be formed by at least one of aninfrared signal, an ultrasonic wave signal and a laser signal.

The signal sensors 63, which are installed at the body 10, receive theinfrared signal or the like. The cleaning controller 241 senses theidentifying signal, through the signal sensing unit 230. When theidentifying signal is sensed, the cleaning controller 241 determines thecharger 80 as an obstacle, and then performs a control operation toprevent the auxiliary cleaning units 21 and 22 from extending. For ageneral obstacle, the cleaning controller 241 performs a controloperation to extend the auxiliary cleaning units 21 and 22 and thus toremove dust from an area disposed adjacent to the obstacle by theauxiliary cleaning units 21 and 22. For the charger 80, however, thecleaning controller 241 performs a control operation to prevent theauxiliary cleaning units 21 and 22 from extending and thus to preventthe body 10 from striking the charger 80 and to prevent the position ofthe charger 80 from being shifted.

FIG. 13 is a view schematically illustrating an operation of the robotcleaner to recognize a charger zone in accordance with anotherembodiment of the present disclosure.

Referring to FIG. 13, the body 10 may dock with the charger 80, forcharging thereof. When the body 10 docks with the charger 80, thecharging terminals 51 of the body 10 contact the charging terminals 81of the charger 80. In this state, the signal sensors 63 receive a signalL transmitted from the signal transmitting unit 82 of the charger 80.Accordingly, the signal sensing unit 230 senses an identifying signalindicating the charger zone. Meanwhile, the charging controller 243senses contact between the charging terminals 51 of the body 10 and thecharging terminals 81 of the charger 80. Although the chargingcontroller 243 may not sense the charging state of the body 10, thecleaning controller 241 may determine that the body 10 is positioned atthe charger zone, when the identifying signal from the charger 80 issensed in a stopped state of the body 10. That is, the cleaningcontroller 241 may perform a control operation to prevent the auxiliarycleaning units 21 and 22 from extending when the body 10 is positionedat the charger zone, for charging thereof.

Meanwhile, FIG. 13 illustrates, as an example of the identifying signal,a signal to guide the body 10 toward the charger 80, for docking of thebody 10 with the charger 80. Of course, the identifying signal is notlimited to the illustrated signal. The identifying signal may also beapplied, in the same manner as described above, to a signal causing thecharger 80 to be sensed as an obstacle, thereby causing the body 10 totravel while bypassing the charger 80. For example, even when a signalto prevent the body 10 from entering the charger 80 is used, the body 10may enter the charger 80. That is, when the body 10 approaches thecharger 80 in a return mode, for charging thereof, it may contact thecharger 80 even if the identifying signal from the charger 80 is sensed.Even when the return mode for charging of the body 10 is completed inaccordance with contact between the body 10 and the charger 80, and thecharging mode starts, the charger 80 may continuously transmit theidentifying signal. Although the cleaning charger 241 may sense thecharger 80 as an obstacle in accordance with sensing of the identifyingsignal from the charger 80, it may determine, based on the stopped stateof the body 10, that the body 10 is positioned at the charger zone, andmay then perform a control operation to prevent the auxiliary cleaningunits 21 and 22 from extending. Thus, it may be possible to prevent theauxiliary cleaning units 21 and 22 from extending during charging of thebody 10 due to sensing of the charger 80 as an obstacle.

FIG. 14 is a view schematically illustrating an operation of the robotcleaner to recognize a charger zone in accordance with anotherembodiment of the present disclosure.

Referring to FIG. 14, the body 10 removes dust from the floor whiletraveling on a cleaning region along a predetermined travel path. Tothis end, the travel controller 242 creates a cleaning region mapincluding information about the travel path of the body 10, and storestravel regions D corresponding to the travel path of the body 10. Thebody 10 removes dust from the floor while traveling on the travelregions D along the travel path.

When a identifying signal L from the charger 80 is sensed on the travelpath of the body 10, the travel controller 242 may designate theposition, from which the identifying signal L is transmitted, to theposition of the charger 80. The travel controller 242 identifies thecharger zone C, based on the position of the charger 80 designated inthe cleaning region map, and does not sense the charger zone C as anobstacle. That is, the travel controller 242 performs a controloperation not only to cause the body 10 to travel while bypassing thecharger zone C, but also to prevent the auxiliary cleaning units 21 and22 from extending. When the auxiliary cleaning units 21 and 22 are in anextended state in the above case, the possibility that the body 10strikes the charger 80 may increase. Also, the position of the charger80 may be shifted due to the striking. To this end, the cleaningcontroller 241 recognizes the charger zone C, and performs a controloperation to prevent the auxiliary cleaning units 21 and 22 fromextending in the charger zone C.

FIG. 14 illustrates, as an example of the identifying signal, a signalto guide the body 10 toward the charger 80, for docking of the body 10with the charger 80. Of course, the identifying signal is not limited tothe illustrated signal. The identifying signal may also be applied, inthe same manner as described above, to a signal causing the charger 80to be sensed as an obstacle, thereby causing the body 10 to travel whilebypassing the charger 80.

FIG. 15 is a view schematically illustrating an operation of the robotcleaner to recognize a virtual obstacle zone in accordance with anexemplary embodiment of the present disclosure.

Referring to FIG. 15, an extension prevention signal generating unit 90forms an extension prevention zone by transmitting an identifyingsignal. The extension prevention zone is a virtual obstacle zone formedby the identifying signal transmitted from the extension preventionsignal generating unit 90. The body 10 is controlled to travel whilebypassing the virtual obstacle zone.

The signal sensing unit 230 provided at the body 10 senses theidentifying signal transmitted from the extension prevention signalgenerating unit 90. Based on the sensed identifying signal, the cleaningcontroller 241 recognizes the extension prevention zone. The signalsensors 63, which are installed at the front and lateral surfaces of thebody 10, as described above, receive the signal transmitted from theextension prevention signal generating unit 90. Based on the signalreceived by the signal sensors 63, the signal sensing unit 230 sensesthe identifying signal.

The identifying signal may form a virtual obstacle zone extending in onedirection from the extension prevention signal generating unit 90 whilehaving a predetermined size. For example, the identifying signal mayform a rectilinear virtual wall zone W having a predetermined thicknessand a predetermined length. When the virtual wall zone W is sensed, thetravel controller 242 performs a control operation to cause the body 10to travel after turning without entering the virtual wall zone W. Sincethe virtual wall zone W is not a floor area, which is disposed adjacentto a wall and at which the auxiliary cleaning units 21 and 22 extend toremove dust, the cleaning controller 241 performs a control operation toprevent the auxiliary cleaning units 21 and 22 from extending when thevirtual wall zone W is sensed. The identifying signal, which forms thevirtual wall zone W, as described above, may include at least one of aninfrared signal, an ultrasonic wave signal and a laser signal, which maybe transmitted from the extension prevention signal generating unit 90in one direction within a certain angular range.

Meanwhile, the identifying signal may form a virtual obstacle zone Rhaving a predetermined curved surface around the extension preventionsignal generating unit 90. In this case, the extension prevention signalgenerating unit 90 prevents access of the body 10 to the virtualobstacle zone R. That is, the identifying signal causes the virtualobstacle zone R around the extension prevention signal generating unit90 to be sensed as an obstacle, thereby causing the body 10 to travelwhile bypassing the extension prevention signal generating unit 90. Inthis case, the cleaning controller 241 performs a control operation toprevent the auxiliary cleaning units 21 and 22 from extending, eventhough it senses the virtual obstacle zone R as an obstacle. This isbecause, when the auxiliary cleaning unit 21 or 22 strikes the extensionprevention signal generating unit 90, the position of the extensionprevention signal generating unit 90 may be shifted, thereby causing thevirtual wall zone W to be varied. Generally, there may be, beyond thevirtual wall zone W, an article, etc., which have a possibility of beingdamaged due to impact. In order to prevent access of the body 10 to suchan article, the user forms the virtual wall zone W, using the extensionprevention signal generating unit 90.

Infrared signals may be used as the identifying signal, which forms thevirtual obstacle zone R having a predetermined curved surface around theextension prevention signal generating unit 90. That is, when aplurality of signal transmitters is installed at a lateral surface ofthe extension prevention signal generating unit 90, to transmit infraredsignals toward the floor at a predetermined angle, a signal zone havinga predetermined curved shape is formed around the extension preventionsignal generating unit 90. Of course, the identifying signal is notlimited to the infrared signal. An ultrasonic wave signal or a lasersignal may be used in the same manner as in the infrared signal.

FIG. 16 is a view schematically illustrating an operation of the robotcleaner to recognize a virtual obstacle zone in accordance with anotherembodiment of the present disclosure.

Referring to FIG. 16, the signal sensing unit 230 may sense a magneticfield signal, in addition to an infrared signal, an ultrasonic wavesignal, or a laser signal. The cleaning controller 241 recognizes anextension prevention zone, based on the sensed magnetic field signal,and then performs a control operation to prevent the auxiliary cleaningunits 21 and 22 from extending.

Meanwhile, the extension prevention zone may be formed by an extensionprevention signal generating unit, which generates a magnetic field. Forexample, as shown in FIG. 16, the extension prevention zone may be amagnetic field zone formed by a magnetic belt M installed on the floor.When the magnetic belt M is disposed on the travel path of the body 10,the travel controller 242 senses the magnetic belt M as an obstacle, andthen performs a control operation to cause the body 10 to travel whilebypassing the magnetic belt M. Also, the cleaning controller 241determines the magnetic field zone as the extension prevention zone, andthen performs a control operation to prevent the auxiliary cleaningunits 21 and 22 from extending. The magnetic belt M is an example of aconfiguration to form a magnetic field zone and, as such, embodiments ofthe present disclosure are not limited thereto. Any device or article,which forms a magnetic field, may form the extension prevention zone inthe same manner as described above.

FIG. 17 is a flowchart schematically illustrating a method forcontrolling the robot cleaner in accordance with an exemplary embodimentof the present disclosure.

Referring to FIG. 17, first, the body 10 performs cleaning by sweepingdust on the floor by the main brush while traveling on the floor inaccordance with a travel algorithm (S310). Simultaneously, sensing of anobstacle on a travel path of the body 10 is carried out through theobstacle sensing unit 220, which is provided at the body 10, totransmit/receive an infrared signal or an ultrasonic wave signal (S320).

When an obstacle is sensed, it is determined whether the region of thesensed obstacle is a charger zone (S330). Recognition of the chargerzone may be achieved in various manners. The robot cleaner 1 may travelabout a cleaning region and determine whether cleaning of the cleaningregion is completed, in accordance with a cleaning region map includinginformation about the travel path of the body 10. In this case,recognition of the charger zone may be achieved by designating the startposition of the travel path of the body 10 to the position of thecharger 80. That is, the position of the charger 80 designated in thecleaning region map may be recognized as the charger zone.

Also, recognition of the charger zone may be achieved using a method ofsensing a charging state of the body 10. That is, when the body 10 isbeing charged, it may be determined that the body 10 is positioned atthe charger zone. In a similar method, recognition of the charger zonemay be achieved through sensing of the charging completion state of thebody 10. That is, when the body 10 travels backward after completingcharging, it may be determined that the body 10 is positioned at thecharger zone for a predetermined time. After completion of charging, thebody 10 returns to a position, at which cleaning was completed forcharging, through backward travel. In this case, it is determined thatthe body 10 is positioned at the charger zone for a predetermined time,in order to prevent the auxiliary cleaning units 21 and 22 fromextending during backward travel of the body 10. Accordingly, it may bepossible to prevent the body from striking the charger 80 duringcharging of the body 10 or after completion of charging.

Recognition of the charger zone may also be achieved using a method inwhich an identifying signal is transmitted from the charger 80, and thetransmitted signal is then sensed. That is, recognition of the chargerzone may be achieved by the signal sensing unit 230, which is providedat the body 10, to sense a identifying signal. In this case, theidentifying signal may be a signal to guide travel of the body 10, fordocking of the body 10 with the charger 80, or a signal to form acharger zone having a predetermined curved surface at the front orlateral side of the charger 80. When an identifying signal is sensed,the obstacle region sensed based on the sensed identifying signal may berecognized as the charger zone. Meanwhile, when the body 10 contacts thecharger 80, for charging thereof, it is in a stopped state. In thisstate, an identifying signal may be sensed. That is, when an identifyingsignal is sensed in a stopped state of the body 10, it may be determinedthat the body 10 is positioned at the charger zone. Also, the position,from which an identifying signal is transmitted, may be designated tothe position of the charger 80, using the cleaning region map, asdescribed above.

When the sensed obstacle region is the charger zone, a control operationis carried out to prevent the auxiliary cleaning units 21 and 22 fromextending (S340). Accordingly, it may be possible to prevent theauxiliary cleaning units 21 and 22 from striking the charger 80 due toextension thereof. Also, the body 10 is controlled to travel whilebypassing the charger 80. Accordingly, it may be possible to prevent thebody 10 from striking the charger 80.

When the sensed obstacle region is not the charger zone, a controloperation is carried out to extend the auxiliary cleaning units 21 and22, and thus to cause the auxiliary cleaning units 21 and 22 to removedust accumulated on an area disposed adjacent to the sensed obstacle(S350).

FIG. 18 is a flowchart schematically illustrating a method forcontrolling the robot cleaner in accordance with another embodiment ofthe present disclosure.

Referring to FIG. 18, first, the body 10 performs cleaning by sweepingdust on the floor by the main brush while traveling on the floor inaccordance with a travel algorithm (S410). Simultaneously, sensing of anobstacle on a travel path of the body 10 is carried out (S420).

When an obstacle is sensed, it is determined whether the region of thesensed obstacle is an extension prevention zone (S430). Recognition ofthe charger zone may be achieved, using an identifying signaltransmitted from the extension prevention signal generating unit 90. Tothis end, the signal sensing unit 230, which senses the identifyingsignal, may be provided at the body 10.

The extension prevention zone may be formed in various manners. Forexample, a virtual obstacle zone extending from the extension preventionsignal generating unit 90 in one direction while having a predeterminedsize may be formed. Alternatively, a virtual obstacle zone having apredetermined curved surface around the extension prevention signalgenerating unit 90 may be formed. Although there is no actual obstaclein the virtual obstacle zone, the virtual obstacle zone is sensed as ifthere is an obstacle in the virtual obstacle zone, so as to control thebody 10 to travel while bypassing the virtual obstacle zone. The virtualobstacle zone is different from obstacle regions in that the auxiliarycleaning units 21 and 22 are prevented from extending in the virtualobstacle zone, as will be described later. As described above, theidentifying signal may include an infrared signal, an ultrasonic wavesignal, or a laser signal.

Meanwhile, the extension prevention zone may be formed in the form of amagnetic field zone. For example, a device or an article, whichgenerates a magnetic field, such as a magnetic belt, may be installed onthe floor. In this case, it may be possible to discriminate theextension prevention zone from obstacle regions through sensing of amagnetic field signal. When a magnetic field zone is sensed, based onthe sensed magnetic field signal, the body 10 is controlled to travelwhile bypassing the magnetic field zone. In this case, the auxiliarycleaning units 21 and 22 may also be controlled to be prevented fromextending. When magnetic sensors are used as the signal sensors providedat the body 10, it may be possible to sense the magnetic field generatedby the magnetic belt or the like.

Formation of the extension prevention zone is not limited to the abovedescribed methods. The extension prevention zone may have the form of anaccess preventing line, to prevent access of the body 10 thereto. Therobot cleaner 1 may sense the access preventing line, through sensing ofan electromagnetic signal or an optical signal, or vision-basedrecognition.

When the sensed obstacle region is the extension prevention zone, acontrol operation is carried out to prevent the auxiliary cleaning units21 and 22 from extending (S440). On the other hand, when the sensedobstacle region is not the extension prevention zone, a controloperation is carried out to extend the auxiliary cleaning units 21 and22, and thus to cause the auxiliary cleaning units 21 and 22 to removedust accumulated on an area disposed adjacent to the sensed obstacle(S450).

The above-described operations of the robot cleaner 1 may be applied tothe exhaust station to exhaust dust collected in the robot cleaner 1 inthe same manner as applied to the charger 80.

Meanwhile, although the auxiliary cleaning units 21 and 22 of the robotcleaner 1 have been described as being coupled to left and light sidesof the body 10 in the above-described embodiments of the presentdisclosure, there is no limitation as to the number of auxiliarycleaning units and the installation positions of auxiliary cleaningunits.

As apparent from the above description, in accordance with one aspect ofthe present disclosure, it may be possible to recognize the charger zoneor extension prevention zone, and thus to prevent the auxiliary cleaningunits from extending. Accordingly, it may be possible to prevent theauxiliary cleaning tool of each auxiliary cleaning unit from striking anadditional device. Since the body travels while bypassing the additionaldevice without striking the additional device, it may be possible toprevent the position of the additional device from being shifted and toprevent the additional device from being damaged. Since the position ofthe additional device, for example, the charger is not shifted, the bodyof the robot cleaner may rapidly return to the charger. When the virtualobstacle zone is employed, it may be possible to protect articlesdisposed beyond the virtual obstacle zone in accordance with user'sdesire because the virtual obstacle zone is not varied.

Although a few embodiments of the present disclosure have been shown anddescribed, it would be appreciated by those skilled in the art thatchanges may be made in these embodiments without departing from theprinciples and spirit of the invention, the scope of which is defined inthe claims and their equivalents.

What is claimed is:
 1. A robot cleaner comprising: a body to travel on afloor; an obstacle sensing unit to sense an obstacle approaching thebody; an auxiliary cleaning unit mounted to a bottom of the body, theauxiliary cleaning unit being configured to be extendable outside of thebody and retractable into the body; and a control unit to control theauxiliary cleaning unit when the obstacle is sensed, wherein the controlunit is configured to recognize a zone of a charger and performs acontrol operation to prevent the auxiliary cleaning unit from extendingwhen the body is in the charger zone.
 2. The robot cleaner according toclaim 1, wherein the control unit creates and stores a cleaning regionmap including information about a travel path of the body.
 3. The robotcleaner according to claim 2, wherein the control unit designates astart position of the travel path of the body to a position of thecharger in the cleaning region map, recognizes the charger zone based onthe charger position designated in the cleaning region map, and performsa control operation to cause the body to travel while bypassing thecharger zone.
 4. The robot cleaner according to claim 1, wherein thecontrol unit determines a charging state of the body.
 5. The robotcleaner according to claim 4, wherein the control unit determines thatthe body is positioned at the charger zone when the body is in acharging state.
 6. The robot cleaner according to claim 4, wherein thecontroller determines that the body is positioned at the charger zonefor a predetermined time, when the body travels backward aftercompletion of charging.
 7. The robot cleaner according to claim 1,further comprising: a signal sensing unit to sense a signal transmittedfrom the charger, wherein the control unit recognizes the charger zonebased on the signal, and performs a control operation to cause the bodyto travel while bypassing the charger zone.
 8. The robot cleaneraccording to claim 7, wherein the signal is a signal to guide travel ofthe body toward the charger, for docking of the body with the charger.9. The robot cleaner according to claim 8, wherein the signal comprisesat least one of an infrared signal, an ultrasonic signal and a lasersignal, which are forwardly or laterally transmitted from the chargerwithin a predetermined angular range.
 10. The robot cleaner according toclaim 8, wherein the signal is divided into two signals, which overlapeach other and have different ranges or different intensities.
 11. Therobot cleaner according to claim 7, wherein the signal forms, as thecharger zone, a zone having a predetermined curved surface at a front orlateral side of the charger.
 12. The robot cleaner according to claim11, wherein the signal comprises at least one of an infrared signal, anultrasonic wave signal and a laser signal, each of which forms a signalzone having a predetermined curved surface at the front or lateral sideof the charger.
 13. The robot cleaner according to claim 11, wherein thesignal is divided into two signals, which overlap each other and havedifferent ranges or different intensities.
 14. The robot cleaneraccording to claim 7, wherein the control unit determines that the bodyis positioned at the charger zone, when the signal is sensed in astopped state of the body.
 15. The robot cleaner according to claim 7,wherein the control unit creates and stores a cleaning region mapincluding information about a travel path of the body, designates aposition, from which the signal is transmitted, to a position of thecharger in the cleaning region map, recognizes the charger zone based onthe charger position designated in the cleaning region map, and performsa control operation to cause the body to travel while bypassing thecharger zone.